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Add a "dumpable" bit to the extent state.

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Currently, this is unused (i.e. all extents are always marked dumpable).  In the
future, we'll begin using this functionality.
This commit is contained in:
David Goldblatt
2017-09-18 17:25:57 -07:00
committed by David Goldblatt
parent bbaa72422b
commit d14bbf8d81
6 changed files with 65 additions and 21 deletions
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36
include/jemalloc/internal/extent_structs.h
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@@ -23,13 +23,14 @@ struct extent_s {
* a: arena_ind
* b: slab
* c: committed
* d: dumpable
* z: zeroed
* t: state
* i: szind
* f: nfree
* n: sn
*
* nnnnnnnn ... nnnnnfff fffffffi iiiiiiit tzcbaaaa aaaaaaaa
* nnnnnnnn ... nnnnffff ffffffii iiiiiitt zdcbaaaa aaaaaaaa
*
* arena_ind: Arena from which this extent came, or all 1 bits if
* unassociated.
@@ -44,6 +45,23 @@ struct extent_s {
* as on a system that overcommits and satisfies physical
* memory needs on demand via soft page faults.
*
* dumpable: The dumpable flag indicates whether or not we've set the
* memory in question to be dumpable. Note that this
* interacts somewhat subtly with user-specified extent hooks,
* since we don't know if *they* are fiddling with
* dumpability (in which case, we don't want to undo whatever
* they're doing). To deal with this scenario, we:
* - Make dumpable false only for memory allocated with the
* default hooks.
* - Only allow memory to go from non-dumpable to dumpable,
* and only once.
* - Never make the OS call to allow dumping when the
* dumpable bit is already set.
* These three constraints mean that we will never
* accidentally dump user memory that the user meant to set
* nondumpable with their extent hooks.
*
*
* zeroed: The zeroed flag is used by extent recycling code to track
* whether memory is zero-filled.
*
@@ -80,25 +98,29 @@ struct extent_s {
#define EXTENT_BITS_COMMITTED_MASK \
((uint64_t)0x1U << EXTENT_BITS_COMMITTED_SHIFT)
#define EXTENT_BITS_ZEROED_SHIFT (MALLOCX_ARENA_BITS + 2)
#define EXTENT_BITS_DUMPABLE_SHIFT (MALLOCX_ARENA_BITS + 2)
#define EXTENT_BITS_DUMPABLE_MASK \
((uint64_t)0x1U << EXTENT_BITS_DUMPABLE_SHIFT)
#define EXTENT_BITS_ZEROED_SHIFT (MALLOCX_ARENA_BITS + 3)
#define EXTENT_BITS_ZEROED_MASK \
((uint64_t)0x1U << EXTENT_BITS_ZEROED_SHIFT)
#define EXTENT_BITS_STATE_SHIFT (MALLOCX_ARENA_BITS + 3)
#define EXTENT_BITS_STATE_SHIFT (MALLOCX_ARENA_BITS + 4)
#define EXTENT_BITS_STATE_MASK \
((uint64_t)0x3U << EXTENT_BITS_STATE_SHIFT)
#define EXTENT_BITS_SZIND_SHIFT (MALLOCX_ARENA_BITS + 5)
#define EXTENT_BITS_SZIND_SHIFT (MALLOCX_ARENA_BITS + 6)
#define EXTENT_BITS_SZIND_MASK \
(((uint64_t)(1U << LG_CEIL_NSIZES) - 1) << EXTENT_BITS_SZIND_SHIFT)
#define EXTENT_BITS_NFREE_SHIFT \
(MALLOCX_ARENA_BITS + 5 + LG_CEIL_NSIZES)
(MALLOCX_ARENA_BITS + 6 + LG_CEIL_NSIZES)
#define EXTENT_BITS_NFREE_MASK \
((uint64_t)((1U << (LG_SLAB_MAXREGS + 1)) - 1) << EXTENT_BITS_NFREE_SHIFT)
#define EXTENT_BITS_SN_SHIFT \
(MALLOCX_ARENA_BITS + 5 + LG_CEIL_NSIZES + (LG_SLAB_MAXREGS + 1))
(MALLOCX_ARENA_BITS + 6 + LG_CEIL_NSIZES + (LG_SLAB_MAXREGS + 1))
#define EXTENT_BITS_SN_MASK (UINT64_MAX << EXTENT_BITS_SN_SHIFT)
/* Pointer to the extent that this structure is responsible for. */
@@ -128,7 +150,7 @@ struct extent_s {
*/
ql_elm(extent_t) ql_link;
/*
/*
* Linkage for per size class sn/address-ordered heaps, and
* for extent_avail
*/